The conventional Bosphorus Cruises start by the Dolmabahçe Palace which would not let you catch the historical peninsula, on the contrary, only our Golden Horn Cruise would let you see the monumental Süleymaniye Mosque Aquadect of Valens, Yeni Mosque, Galata Tower, Beyazıt Tower, Topkapı Palace and Hagia Sophia from an unique angle of view.
The first answer covers partly this question too: The public boat does not cover Golden Horn which is a big miss for one who wants to see Istanbul properly. But that's not all, as you can see on the right photo, public boat is passing few hundred meters to the shores (because of its size) which means you may not see the most beautiful houses and palaces good enough. If you dont care about the distance maybe speed would call your attention: public boats sail by 16 MPH which is more than twice of our curise ship's speed That means you would have much less time to take photo or enjoy details. But you should be guessing this, we're talking about public boat which aim is taking people from palace in a quickest way.
Another very important advantage of joining our private cruise is having a professional guide with you during all the curise which is not existing on a public boat. If you consider that you are going to cruise along the shores of a 3000 years old city, you would understand much better the importance of the guidence.
Maybe we should first point out what is "Legal Tour". Such a tour should be organised and provided by an A Grade Travel Agency certificated by TURSAB (Turkish Association of Travel Agencies) and accompanied by a cocarted professional Tourist Guide.
Actually nothing happens, until something happens! What does it mean? It means if you are lucky enough, you dont realise any problem, but if a problem or an accident occurs, you find ypır sef in a big trouble, because you will not have any legal person spoken to, even your insurance company may refuse to cover your losses as they would have no collocutor to deal with.